dart - 使用包装好的数组测试流

Question

我正在尝试测试emitArray函数发出的Response.Success，其值为['test']。
如果我发出List<String>，则一切正常，但是一旦将结果列表包装在Response<List<String>>中，测试将失败。

发出结果，但与预期结果比较时失败。
我想知道它是否与==中Response.Success的实现有关，我在使用IDE提供的默认实现。

这不是我拥有的真实代码，它只是一个简单的示例，在尝试识别问题时更容易理解。

这是我要测试的类(class):

class ListResponse {
  final _array = BehaviorSubject<Response<List<String>>>();

  Stream<Response<List<String>>> get array => _array.stream;

  Future<void> emitArray() async {
    _array.add(Response.success(['test']));
  }

  void dispose() {
    _array.close();
  }
}

这是我的测试:

void main() {
  ListResponse underTest;
  setUp(() {
    underTest = ListResponse();
  });

  test('It should emit array', () {
    final array = Response.success(['test']);

    expect(
      underTest.array,
      emitsInOrder([
        array,
        emitsDone,
      ]),
    );

    underTest.emitArray();

    underTest.dispose();
  });
}

这是它引发的错误:

Expected: should do the following in order:
          • emit an event that SuccessResponse<List<String>>:<SuccessResponse{value: [test]}>
          • be done
  Actual: <Instance of 'BehaviorSubject<Response<List<String>>>'>
   Which: emitted • SuccessResponse{value: [test]}
                  x Stream closed.
            which didn't emit an event that SuccessResponse<List<String>>:<SuccessResponse{value: [test]}>

这是Response类

class Response<T> {
  Response._();

  factory Response.success(T value) = SuccessResponse<T>;
  factory Response.error(Exception error) = ErrorResponse<T>;
}

class ErrorResponse<T> extends Response<T> {
  ErrorResponse(this.error): super._();

  final Exception error;

  @override
  bool operator ==(Object other) =>
      identical(this, other) ||
          other is ErrorResponse &&
              runtimeType == other.runtimeType &&
              error == other.error;

  @override
  int get hashCode => error.hashCode;

  @override
  String toString() {
    return 'ErrorResponse{error: $error}';
  }
}

class SuccessResponse<T> extends Response<T> {
  SuccessResponse(this.value): super._();

  final T value;

  @override
  bool operator ==(Object other) =>
      identical(this, other) ||
          other is SuccessResponse &&
              runtimeType == other.runtimeType &&
              value == other.value;

  @override
  int get hashCode => value.hashCode;

  @override
  String toString() {
    return 'SuccessResponse{value: $value}';
  }
}

Answer 1

I'm wondering if it's related to the implementation of == in Response.Success

究竟。此特定测试失败，因为您无法将列表与 ==进行比较:

abstract class List<E> implements EfficientLengthIterable<E> {
  ...
  /**
  * Whether this list is equal to [other].
  *
  * Lists are, by default, only equal to themselves.
  * Even if [other] is also a list, the equality comparison
  * does not compare the elements of the two lists.
  */
 bool operator ==(Object other);
}

解决方法是，您可以更改实现以比较对象的字符串表示形式:

  @override
  bool operator ==(Object other) =>
      identical(this, other) ||
      other is SuccessResponse &&
          runtimeType == other.runtimeType &&
          value.toString() == other.value.toString();

有趣的是，传递未包装的 List<String>的对象通过了测试。发生这种情况是因为 StreamMatcher使用 equals()包中的 matcher来匹配事件，以及 equals() can match lists and maps。它首先尝试使用 ==匹配对象，然后检查它们是否为Iterable / Set / Map(并与它们进行递归深度匹配)，然后报告不匹配错误。